搅拌槽内气液两相混沌混合及分散特性  

Chaotic mixing and dispersing characteristics of gas-liquid two phases in stirred tank

作　　者：谷德银[1] 刘作华[1] 张姬一哲 邱发成 李军[1] 陶长元[1] 王运东[2] 

机构地区：[1]重庆大学化学化工学院,重庆400044 [2]化学工程联合国家重点实验室清华大学,北京100084

出　　处：《化工学报》2018年第2期625-632,共8页CIESC Journal

基　　金：国家自然科学基金项目(21576033;21636004);国家重点研发计划项目(2017YFB0603105);国家科技支撑计划项目(2015BAB17B01);中央高校基本科研业务费专项(106112017CDJQJ228808);重庆市社会事业与民生保障科技创新专项(cstc2015shmszx100024)~~

摘　　要：传统Rushton刚性桨常应用于过程工业中搅拌反应器内的气液分散过程,但由于桨叶背后易形成较大的气穴,气液混合效果较差。为了提高搅拌槽内气液两相的混合效果,提出了一种刚柔组合桨强化气液两相的分散过程。利用Lab VIEW软件处理刚性桨和刚柔组合桨体系中气液混合过程的压力脉动信号,通过Matlab软件编程计算最大Lyapunov指数(LLE),分析气液混合体系的混沌混合行为,同时,对刚性桨和刚柔组合桨体系中的相对搅拌功耗、整体气含率、局部气含率进行测量。结果表明,在功耗为170 W,通气量为10 m3?h-1条件下,与刚性桨相比,刚柔组合桨能够通过刚-柔-流的耦合作用促进桨叶能量的传递过程,提高搅拌体系的混沌混合程度,刚柔组合桨体系的LLE提高了8.89%。同时,在相同操作条件下,与刚性桨相比,刚柔组合桨能够有效提高相对搅拌功耗以及搅拌槽内的整体气含率和局部气含率,且搅拌槽内气体分散更为均匀。Traditional Rushton rigid impeller is often applied to gas-liquid dispersion process in industrial stirred tank reactors. However, poor gas dispersion capacity is occurred behind impeller blades due to easy formation of gas cavitation. In order to improve gas-liquid mixing performance, a rigid-flexible impeller was proposed to intensify gas dispersion process. Time series data of pressure fluctuation were recorded by Lab VIEW and the largest Lyapunov exponent（LLE） was calculated by Matlab to analyze chaotic characteristics of gas-liquid mixing behavior, while relative power demand, total gas holdup, and local gas holdup were measured simultaneously in stirred tank with a rigid impeller or a rigid-flexible impeller. Results showed that, under condition of power consumption at 170 W and gas flowrate at 10 m^3·h^-1, rigid-flexible impeller could strengthen energy transfer and enhance chaotic mixing through rigid-flexible-flow interaction. LLE value of rigid-flexible impeller system was 8.89% higher than that of rigid impeller system. Rigid-flexible impeller could improve relative power demand, total gas holdup, local gas holdup, and more homogeneously gas dispersion, compared to rigid impeller at the same operating conditions.

关 键 词：气液搅拌反应器 刚柔组合桨 气液分散 混沌混合 

分 类 号：TQ027.2[化学工程]